1. Field of the Invention
The present invention relates to a photo printer for forming a color image on a rolled paper on which heat-sensitive color developing layers of yellow, magenta, and cyan are formed.
2. Description of the Related Art
In the relate art, there was a photo printer for forming a color image on a rolled paper on which heat-sensitive color developing layers of yellow, magenta, and cyan are formed. A general photo printer forms a color image by performing a series of procedures described below from (1) to (6) as shown in Patent Documents 1 and 2. The respective procedures in (1) to (6) are performed for an image forming area on which a color image of this time is formed while feeding or retracting the rolled paper.
(1) Perform heat-sensitive printing on a heat-sensitive yellow color developing layer to form an yellow image;
(2) Perform exposure using an yellow fixing lamp to fix the yellow image;
(3) Perform heat-sensitive printing on a heat-sensitive magenta color developing layer to form a magenta image;
(4) Perform exposure using a magenta fixing lamp to fix the magenta image;
(5) Perform heat-sensitive printing on a heat-sensitive cyan color developing layer to form a cyan image;
(6) Cut the image formed area off the rolled paper and discharge the same.
The cyan image is fixed by being exposed by an ultraviolet ray contained in natural light.
The photo printer is provided with a shutter, which is shown in JP-A-10-29328 and JP-A-2001-239687, for reducing a no image forming area which is exposed by the fixing lamp in the vicinity of the boundary between the portion where the image is to be formed this time (image forming area) and the portion where no image is to be formed (no image forming area). Since the no image forming area which is exposed by the fixing lamp cannot be used for the next image formation and hence is wasted, the shutter is provided for reducing the portion to be wasted, and utilizing the rolled paper effectively. More specifically, the shutter covers the no image forming area when the portion in the vicinity of the boundary between the image forming area and the no image forming area is transported through the position to be exposed by the fixing lamp, so as to prevent the no image forming area from being exposed.
However, the photo printer shown in JP-A-10-29328 has a structure in which the shutter is moved by a drive force of a feeding motor for feeding the rolled paper, and is provided with a electromagnetic clutch for switching between a state in which the drive force of the feeding motor is transmitted to the shutter to start the movement of the shutter and a state in which the drive force is not transmitted thereto when the shutter reaches an adequate position with respect to the rolled paper being fed, that is, the position to cover the no image forming area from the position in the vicinity of the boundary between the image forming area and the no image forming area for performing exposure by the fixing lamp. The drive force of the feeding motor is transmitted to the shutter via a plurality of gears. The electromagnetic clutch is provided in the gear group. Therefore, the structure of the gear group for transmitting the drive force of the feeding motor to the shutter is complicated, and a device body is expensive.
On the other hand, since the photo printer disclosed in JP-A-2001-239687 is provided with a motor for moving the shutter and a motor for feeding the rolled paper separately, it is not necessary to provide the electromagnetic clutch for moving the shutter, and hence the structure of the gear group may be simplified. However, since the two motors are provided, there arises a problem in that the device body is upsized, and hence the cost is increased.